The present invention relates to liquid atomizing nozzles. More specifically, but without limitation, the present invention relates to an adjustable, portable, hand held device that is especially useful to mix and atomize two or more fluids for fire protection. Fluorocarbon based fire extinguishing agents are allegedly environmentally harmful since they apparently cause depletion of the Earth's ozone layer. Present United States law and United States treaty agreements require the replacement and phasing out of such materials under the 1988 Montreal Protocol, which classified Halon as a Class I Ozone Depleting Substance (ODS). In addition, the United States Clean Air Act Amendments of 1990 called for a ban on production of Halon in the United States after January 1994.
These laws also prohibited the purposeful venting of these harmful substances and required training of the personnel involved in their use in an attempt to minimize the emission of such substances into the atmosphere. The United States Navy has responded to these prohibitions and requirements by itself prohibiting the use of OSDs in new procurement contracts. To find replacements for traditional systems using banned substances, the Navy continues to conduct research to find new ways and alternate designs for fire extinguishing systems.
Fine Water Mist (FWM) type systems have very favorable characteristics as replacements for existing Halon systems and are continuing to be studied by Navy scientists and engineers. Typically, these systems include nozzles for creating misting fluids using pressurized gas and continue to show favor as a mechanism for fire prevention. In these systems, a liquid is typically directed into a central bore of the nozzle, the central bore directing a flow of high velocity gas. In some nozzles, the velocity and pressure of the gas are increased in a narrowed throat area of the bore which causes the atomization of the fluid into small droplets as the gas travels through the nozzle. To aid atomization and provide an unobstructed flow path of the gas, the fluid is usually injected into the gas stream through an aperture in the bore wall so that the two different fluid streams impinge at approximately a 90 degree angle. Nozzles of the above described type require high pressure spraying of the liquid and the gas. This is undesirable. Another problem with mixing nozzles of this type is the need for fine holes, e.g. holes of a small diameter. These small holes are easily clogged and worn causing the mixture to exit the nozzle at a reduced level of efficiency and effectiveness.
The use of liquid only, water based systems for fire extinguishment is effective and these systems create water droplets by deflecting the water flow just ahead of the spouting aperture. However, the droplet size is large and the desirable fine water mist cannot be achieved.
Therefore, the need for a low pressure, reliable liquid/gas mixing nozzle is desirable and is achieved in U.S. Pat. No. 5,520,331 entitled “Liquid Atomizing Nozzle” which is hereby incorporated by reference. This patent discloses a nozzle structure that produces an extremely fine liquid atomization through low pressurization of the liquid and gas being delivered to the nozzle. The fluid and gas are delivered through relatively large apertures thus effecting minimal wear and clogging of those apertures. In this patent, the nozzle disclosed is a convergent/divergent nozzle, hereinafter referred to as a “C-D” gas nozzle attached to a mixing block having a delivery tube with an aperture that is centered within a gas conduit located upstream of a narrowed throat. However, there is no apparatus disclosed or suggested for controlling/adjusting the output of the C-D nozzle or adapted to allow use of the C-D nozzle in particular environments.
There is therefore a need for replacement designs for existing Halon systems, especially in the areas of fire suppression and also in the areas of first responders, to provide an apparatus, using the C-D nozzle, for effective and efficient fire fighting and to quickly prevent fires from spreading. There is also a need for an apparatus for otherwise delivering the output of the C-D nozzle in a manner that permits the operator to effectively control and tailor the output in the most efficient manner in a package that can be portable and easy to handle by a single operator.